Purity, formulations and chromatography

• What is a pure substance?

  A pure substance is a single element or compound, not mixed with any other substance.
• What happens to pure substances at specific temperatures?

  They melt and boil at specific temperatures.
• How can melting and boiling points be used in chemistry?

  They can be used to distinguish pure substances from mixtures.
• How is a pure substance defined in everyday language?

  A pure substance is one that has had nothing added to it, making it unadulterated and in its natural state.
• Give an example of a pure substance.

  Pure milk is an example of a pure substance.
• What is a formulation?

  A formulation is a mixture that has been designed as a useful product.
• Why are many products considered complex mixtures?

  Each chemical in a complex mixture has a particular purpose.
• How are formulations created?

  Formulations are made by mixing components in carefully measured quantities.
• Name some examples of formulations.

  Examples include fuels, cleaning agents, paints, medicines, alloys, fertilizers, and foods.
• What is the purpose of chromatography?

  Chromatography is used to separate mixtures and provide information to help identify substances.
• What are the two phases involved in chromatography?

  Chromatography involves a stationary phase and a mobile phase.
• How does separation in chromatography depend on the substances involved?

  Separation depends on the distribution of substances between the stationary and mobile phases.
• What is the formula for calculating the Rf value?

  Rf value = distance moved by substance ÷ distance moved by solvent.
• How do different compounds behave in chromatography?

  Different compounds have different Rf values in different solvents, aiding in their identification.
• What happens to a pure compound in chromatography?

  A pure compound will produce a single spot in all solvents.
• What is paper chromatography?

  Paper chromatography is an analytical technique separating compounds by their relative speeds in a solvent as it spreads through paper.
• How does solubility affect the movement of substances in paper chromatography?

  The more soluble a substance is, the further up the paper it travels.
• What is a pigment?

  A pigment is a solid, colored substance.
• What are the key characteristics of pure substances and formulations?

  • Pure substances: single element or compound, specific melting and boiling points, unadulterated.
  • Formulations: designed mixtures, each component has a purpose, created in measured quantities.
• What are the steps involved in chromatography and its significance?

  1. Involves stationary and mobile phases.
  2. Separation based on distribution between phases.
  3. Rf value calculation for identification.
  4. Used to separate and identify compounds in mixtures.